Underwater Light Having Programmable Controller And Replaceable Light-Emitting Diode (LED) Assembly

ABSTRACT

An underwater light including a programmable controller and a replaceable light-emitting diode (LED) printed circuit board assembly (PCBA) is provided. The light includes a controller PCBA in communication with the LED PCBA, and a connector for connecting the controller PCBA to the LED PCBA. An optically-transparent potting compound encapsulates the LED PCBA, and the LED PCBA can be safely replaced by removing a rear housing of the underwater light.

RELATED APPLICATIONS

The present application claims benefit of priority to U.S. ProvisionalPatent Application No. 62/814,763, filed on Mar. 6, 2019, the entiredisclosure of which is hereby incorporated by reference.

BACKGROUND Technical Field

The present disclosure relates generally to the field of underwaterlights for pools and spas. More specifically, the present disclosurerelates to an underwater light having a programmable controller and areplaceable light-emitting diode (LED) printed circuit board assembly(PCBA).

Related Art

In the underwater lighting field, submersible luminaires are known andcommonly used. These devices are conventionally made from a combinationof metal, plastic, and glass. The various electrical components within asubmersible luminaire housing generate heat. As a result of theforegoing, it would be desirable to provide a submersible luminaireincluding a programmable controller configured to optimize luminairelight shows and monitor an input voltage and temperature of the variouselectrical components.

In submersible luminaires, one or more light-emitting elements (e.g.light emitting diodes (LEDs)) mounted on a printed circuit board (PCB)within the submersible luminaire housing can become inoperable due toextended use or for other reasons. Conventional luminaires arehermetically sealed and, therefore, the entire luminaire must bereplaced when LEDs are inoperable (e.g., when LEDs burn out). As aresult of the foregoing, it would be desirable to provide a submersibleluminaire with a replaceable PCB to avoid replacing a luminaire in itsentirety when LEDs mounted on the PCB are inoperable.

Accordingly, the underwater light of the present disclosure addressesthese and other needs.

SUMMARY

The present disclosure relates to an underwater light having aprogrammable controller and a replaceable light-emitting diode (LED)printed circuit board assembly (PCBA). The programmable controllerincludes a controller PCBA in communication with the LED PCBA, and aconnector for connecting the controller PCBA to the LED PCBA. Anoptically-transparent potting compound encapsulates the LED PCBA, andthe LED PCBA can be safely replaced by removing a rear housing of theunderwater light.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the present disclosure will be apparent fromthe following Detailed Description of the Invention, taken in connectionwith the accompanying drawings, in which:

FIG. 1 is a block diagram of the underwater light of the presentdisclosure, illustrating connection of the controller PCBA to the LEDPCBA via the connector;

FIG. 2 is a block diagram of the controller PCBA of FIG. 1;

FIG. 3 is a detailed block diagram of the power subsystem of thecontroller PCBA of FIG. 2;

FIG. 4 is a detailed block diagram of the microcontroller subsystem ofthe controller PCBA of FIG. 2;

FIG. 5 is a detailed block diagram of the LED driver subsystem of thecontroller PCBA of FIG. 2;

FIG. 6 is a detailed block diagram of the LED PCBA of FIG. 1;

FIG. 7 is a circuit diagram of an electromagnetic interference (EMI)filter of the controller PCBA power subsystem of FIG. 3;

FIG. 8 is a circuit diagram of a line frequency detector of thecontroller PCBA power subsystem of FIG. 3;

FIG. 9 is a circuit diagram of a bridge rectifier of the controller PCBApower subsystem of FIG. 3;

FIG. 10 is an oscillogram illustrating an output of the bridge rectifierof FIG. 9;

FIG. 11 is a graph illustrating a switching frequency of an oscillatorof a power correction controller of the controller PCBA power subsystemof FIG. 3;

FIG. 12 is a circuit diagram of a high temperature shutdown circuit ofthe LED PCBA of FIG. 6; and

FIG. 13 is a circuit diagram of an electrically erasable programmableread-only memory (EEPROM) of the LED PCBA of FIG. 6.

DETAILED DESCRIPTION

The present disclosure relates to an underwater light having aprogrammable controller and a replaceable light-emitting diode (LED)printed circuit board assembly (PCBA), as described in detail below inconnection with FIGS. 1-13.

Referring to FIGS. 1-6, the underwater light 10 of the presentdisclosure includes a controller PCBA 12 connected to the LED PCBA 16via a surface mount technology (SMT) connector 14. For example, thecontroller PCBA 12 can connect to the LED PCBA 16 via a vertical SMTconnector having a 16 pin double row configuration. The pins of theconnector 14 can be gold plated and have a power rating of 405 voltsalternating current (VAC) or 572 volts direct current (VDC) and acurrent rating of 5.2 amperes (A). The controller PCBA 12 includes apower subsystem 20, a microcontroller subsystem 22 and an LED driversubsystem 24.

The power subsystem 20 of the controller PCBA 12 powers the LED PCBA 16with a rectified voltage. The LED driver subsystem 24 of the controllerPCBA 12 connects to and drives a plurality of LED strings 74 of the LEDPCBA 16. The LEDs of the LED strings 74 could include red, royal blue,green and white LEDs. In addition, the controller PCBA microcontrollersubsystem 22 can control the LED PCBA 16 based on signals from at leastone of a plurality of thermistors 70 (e.g., LED temperature signals), ahigh temperature shutdown circuit 76 (e.g., shutdown) and anelectrically erasable programmable read-only memory (EEPROM) 72 (e.g.,control signals) of the LED PCBA 16.

The underwater light 10 can monitor the temperature of the controllerPCBA 12 and the LED PCBA 16 and prevent a temperature of the LED PCBA 16from exceeding a temperature threshold by dimming a light output of theLED strings 74 of the LED PCBA 16. The underwater light 10 can alsomonitor an input voltage of the microcontroller subsystem 22 and dim thelight output of the LED PCBA 16 if the input voltage falls below atemperature threshold.

FIG. 2 is a block diagram of the controller PCBA 12 of FIG. 1. Asmentioned above, the controller PCBA 12 includes the power subsystem 20,the microcontroller subsystem 22 and the LED driver subsystem 24. Thecontroller PCBA 14 can connect to the LED PCBA 16 via the SMT connector14.

FIG. 3 is a detailed block diagram of the power subsystem 20 of thecontroller PCBA of FIG. 2. The power subsystem 20 includes anelectromagnetic interference (EMI) filter 30; a bridge rectifier circuit32 which produces a rectified voltage signal; a power factor correction(PFC) controller 34; a bus line (VBUS); a VBUS monitor 36; a linevoltage monitor 38; a linear voltage regulator 40; and a line frequencydetection circuit 42. These components are discussed in further detailbelow.

The controller PCBA 12 is configured to receive an input voltage of 14VAC at a frequency of 50 hertz (Hz) from a European power grid or 60 Hzfrom a North American power grid. The input voltage is received insingle phase and can be provided by a 14 V tap of an isolated,low-voltage step-down transformer. The controller PCBA 12 is configuredto receive the 14 VAC input voltage via a low-voltage AC inputconnection such as two pins (not shown) mounted on the controller PCBA12. The pins can be received by two barrel receptacles (not shown) thatcan be connected to a power cord of the underwater light. The pins andbarrels can have a current rating of 15 A.

FIG. 4 is a detailed block diagram of the microcontroller subsystem 22of the controller PCBA of FIG. 2. The microcontroller subsystem 22 caninclude any suitable microcontroller 50 capable of executing firmwarefor controlling operation of the underwater light. The microcontroller50 can have a clock speed of 20.97 megahertz (MHz) and can operatewithin a 1.71 V to 3.6 V range when power is applied by the 3.3 V linearvoltage regulator 40. When power is removed, the microcontroller 50 canenter a low power mode such that 3.3 V linear voltage regulator 40 canbe required to power the microcontroller 50 for at least 15 seconds.

The microcontroller 50 can control a temperature of the LED PCBA 16 bymonitoring signals from at least one of the plurality of 100 kΩthermistors 70 (e.g., LED Temperature Signals) of the LED PCBA 16. Inaddition, the microcontroller 50 can also control a temperature of thecontroller PCBA 12 by monitoring a 100 kΩ thermistor (not shown) of thecontroller PCBA 12. For example, the underwater light firmware can reactwhen a temperature threshold is exceeded by at least one of thecontroller PCBA 12 and the LED PCBA 16 by gradually reducing a lightoutput of the LED strings 74 such that the reduced light output is notperceptible to a user.

As discussed below, the PFC controller 34 has a high-temperaturefail-safe protection feature that causes the PFC controller 34 to enterthe standby mode when the LED PCBA 16 exceeds a temperature threshold(e.g., 95° C.). Specifically, the PFC controller 34 enters the standbymode (thereby turning off the buck current regulators 60) when a voltagecompensation (VCOMP) pin is pulled low. The VCOMP pin is pulled low viaan n-channel FET that is connected to an open drain pin of a hightemperature shutdown circuit 76. The open drain pin of the hightemperature shutdown circuit 76 can also be connected to a pin of themicrocontroller 50, and the microcontroller 50 can monitor the pin toprovide options for additional responses when the LED PCBA 16 exceedsthe temperature threshold.

The microcontroller 50 can also control a sequence of the light showsand the colors therein via a hall sensor integrated circuit (IC). Thehall sensor IC can be any suitable sensor capable of functioning as anopen drain, omnipolar switch wherein the sensor can toggle through lightshows and colors of the LED strings 74 with a magnetic field in the samemanner as toggling power. The hall sensor IC can be powered by a 3.3 Vsignal from a pin of the microcontroller 50 such that when a signal onthe pin is pulled low, the microcontroller 50 responds by switching tothe next light show in a sequence and/or LED string color.

FIG. 5 is a detailed block diagram of the LED driver subsystem 24 of thecontroller PCBA of FIG. 2. The LED driver subsystem 24 can include aplurality of 1.5 amp (A) step-down (buck) current regulators 60 whereineach buck current regulator 60 has an integrated high side switchingmetal-oxide-semiconductor field-effect transistor (MOSFET) to drive arespective LED string 74 (e.g., red, blue, green, and white LEDstrings).

The input voltage to the buck current regulators 60 is provided by the28 V output voltage of the PFC controller 34. The input supply voltagerange is 4.5 V-42 V. The buck current regulators 60 require a minimumvoltage (VIN) of 26 V to start and therefore an adjustable under voltagelockout (UVLO) pin can be set with a resistor divider to the required 26V input voltage. It is noted that the UVLO protection feature is fordevice protection and does not contain hysteresis. The buck currentregulators 60 can enter low-power mode, thereby removing an inputvoltage to the LED strings 74, when the input voltage falls to 25 V dueto the PFC controller 34 entering the standby mode. The followingequations can be used to set the UVLO hysteresis (1) and the startvoltage (2):

R1=(V _(HYS)(V _(E) N−(I1×R _(ESD)))−I _(HYS) ×R _(ESD) ×V _(START))/I_(HYS) ×V _(EN); and  (1)

R2=R1(V _(EN)−(R _(ESD)×(I1+I _(HYS))))/(V _(STOP) −V _(EN))+(I1+I_(HYS))×(R1+R _(ESD))  (2)

wherein

-   -   V_(HYS)=V_(START)−V_(STOP)    -   R_(ESD)=10 kΩ    -   I1=1 μA    -   I_(HYS)=2.9 μA

A switching frequency of the buck current regulators 60 can be set toapproximately 400 kHz wherein a 301 kΩ resistor is connected to aresistor timing pin and ground. The required resistance can becalculated with the following equation:

R _(RT)(kΩ)=206033/(f _(SW))^(1.092) (kHz)

-   -   wherein    -   f_(SW)=(206033/R_(RT)(kΩ)^((1/1.092))

Current provided to the LED strings 74 can be set and controlled by ananalog current adjustment pin (IADJ). The IADJ pin is driven by adigital to analog converter (DAC) output from the microcontroller 50.The following equation illustrates the relationship between (a) thevoltage applied from the DAC output to the IADJ pin input and (b) thecurrent regulation set point voltage across the sense resistor that iscoupled to a current sense (ISENSE) pin:

V _(ISENSE) =V _(IADJ)/6

The following equation illustrates a calculation for the sense resistorvalue:

R _(ISENSE) =V _(ISENSE) /I _(LED)

The red LED string can be provided with a maximum current of 0.7 A whilethe green, royal blue and white LED strings can be provided with amaximum current of 1.0 A.

Each buck current regulator 60 can have separate inputs for analogdimming and pulse width modulation (PWM) dimming and is configured tooperate at a user selected fixed frequency. The buck current regulators60 receive, at respective dimming input pins (PDIM), PWM input signalsfrom the microcontroller 50 that control a brightness level of the LEDstrings 74 and the moving light shows. The red and blue LED PWM inputsignals can be left justified and the green and white PWM input signalscan be right justified to prevent all four MOSFETs from turning on atthe same time and thereby causing a reduction of the VBUS voltage whichpowers the buck current regulators 60. The signals are not inverted suchthat the LED strings 74 will be on during the t_(on) portion of the dutycycle.

The PWM frequency can be between 100 Hz and 1 kHz and the signal dutycycle will vary based on color, brightness and the moving light show.The PDIM pin has a 1 μA internal pull-up current source which creates adefault on state when the PDIM pin is floating. Accordingly, the PDIMpin has a 10 kΩ pull down resistor to ground to ensure the LED strings74 are in an off state when they are intended to be turned off.Frequency compensation components can be coupled to the compensation(COMP) pin of each buck current regulator 60 for stabilization. Forexample, a 0.1 μF capacitor can be coupled from the COMP pin to groundfor stabilization. If an application requires a faster response to inputvoltage transients, then a 0.01 μF capacitor can be used.

In addition, each buck current regulator 60 can also includecycle-by-cycle overcurrent protection and thermal shutdown protection.An overcurrent situation can occur if the sense resistor shorts, or adirect short occurs between the output and ground. If an overcurrentsituation occurs, the voltage on the ISENSE pin will fall to 0 V, which,in turn, causes the voltage on the COMP pin to rise. When the voltage onthe COMP pin reaches approximately 2.2 V, the voltage is internallyclamped and functions as a MOSFET current limit. The internal MOSFETcurrent can be limited to 6 A. If the overcurrent situation continues, atemperature of a junction of the buck current regulator will rise. Thethermal shutdown circuit protects the buck current regulators 60 bycausing the buck current regulators 60 to enter an off state if thetemperature reaches 165° C. The buck current regulators 60 can enter theon state after the temperature falls below 20° C.

FIG. 6 is a detailed block diagram of the LED PCBA 16 of FIG. 1. The LEDPCBA 16 can include a plurality of thermistors 70; the high temperatureshutdown circuit 76; an electrically erasable programmable read-onlymemory (EEPROM) 72; and the LED strings 74. Specifically, the LED PCBA16 can include three 100 k Ohm (Q) thermistors that the firmware willuse to monitor a temperature of the LED PCBA 16. If the firmware detectsthat a temperature of the LED PCBA 16 exceeds a temperature threshold, acontrol loop algorithm can adjust an intensity of the LED strings 74 tomaintain a maximum LED PCBA 16 temperature of 90° C. The LEDs of the LEDstrings 74 can include red, blue, green and white LEDs. The LED PCBA 16can connect to the controller PCBA 12 via the SMT connector 46. The pinsof the connector can be gold plated and have a power rating of 405 VACor 572 VDC and current rating of 5.2 A. The components are discussed infurther detail below.

FIG. 7 is a circuit diagram of the EMI filter 30 of the controller PCBApower subsystem 20 of FIG. 3. The EMI filter 30 includes capacitors 80 aand 80 b and a common mode choke 82. The capacitors 80 a and 80 b can betwo line to neutral 1.0 mircofarad (μF) ceramic capacitors and complywith electromagnetic compatibility (EMC) class B regulations forresidential use. As mentioned above, the input voltage to the controllerPCBA 12 is received in single phase and can be provided by the 14 V tapof the isolated low voltage step down transformer. The isolated lowvoltage step down transformer protects the controller PCBA 12 from powersurges.

FIG. 8 is a circuit diagram of the line frequency detection circuit 42of the controller PCBA power subsystem 20 of FIG. 3. The line frequencydetection circuit 42 includes 10 kΩ resistors 90 a and 90 b; a 0.1 ρFcapacitor 92; 100 kΩ resistors 94 a and 94 b; a 402 kΩ resistor 96; andan n-channel MOSFET 98. The line frequency detection circuit 42 receivesthe 14 VAC input voltage before it is rectified. The 50 Hz or 60 Hzinput signal is reduced by half and controls the gate of the n-channelMOSFET 98. The drain of the MOSFET 98 is tied to the 3.3 V linearvoltage regulator 40 via the 100 kΩ resistor 94 b (i.e., pull upresistor 94 b). The drain voltage is inverted to match a phase of thegate voltage and is received by the microcontroller 40 as a digitalinput signal. The microcontroller 50 can use the digital input signal todetermine an amount of time that the input voltage has been removed anda timing of light shows by the underwater light.

FIG. 9 is a circuit diagram of the bridge rectifier circuit 32 of thecontroller PCBA power subsystem 20 of FIG. 3. The bridge rectifiercircuit 32 includes 2 kΩ resistors 100 a-100 e, p-channel MOSFETS 102 aand 102 b, n-channel MOSFETS 104 a and 104 b and diodes 106 a-106 d. Thebridge rectifier circuit 32 produces a rectified voltage signal. At thestart of an AC cycle, the diodes 106 a-106 d conduct current until thevoltage meets a threshold to turn on the p-channel MOSFETS 102 a and 102b and n-channel MOSFETS 104 a and 104 b. Specifically, each half-cycleof the alternating input voltage turns on an alternating pair of thep-channel MOSFETS 102 a and 102 b and the n-channel MOSFETS 104 a and104 b to produce a pulsating 120 Hz DC voltage signal. FIG. 10 is anoscillogram illustrating an output of the bridge rectifier circuit 32 ofFIG. 9.

As shown in FIG. 3, the PFC controller 34 receives the rectified voltagesignal from the bridge rectifier circuit 32 and can be any suitable PFCcontroller configured to achieve high power factor, low currentdistortion, and voltage regulation of boost pre-regulators. For example,the PFC controller 34 can be an active PFC controller that operatesunder continuous conduction mode (CCM) and at a programmable fixedfrequency. For example, FIG. 11 is a graph illustrating a switchingfrequency of an oscillator of the PFC controller 34 set at 105 kHz.

The rectified voltage signal (PFC controller 34 input voltage) can bemonitored by the microcontroller 50 wherein the microcontroller 50 couldreduce a lumen output of the LED strings 74 if a voltage conditionregarding the 14 VAC input of the underwater light occurs. For example,a voltage condition could occur when the PFC controller 34 input voltagefalls below 9.0 V because any one of an abnormally low line voltage tothe transformer input, the transformer output being wired to theincorrect tap, the transformer being overloaded or the transformer beingimproperly wired. The lumen output of the LED strings 74 can be reducedwhen the PFC controller 34 input voltage falls below 9.0 V to preventhigh, and potentially dangerous, input currents into the underwaterlight as the PFC controller 34 attempts to compensate for the lowervoltage with a higher current. The rectified voltage signal is receivedby the microcontroller 50 before the signal is boosted to 28 V by thePFC controller 34. Specifically, the rectified voltage signal passesthrough a blocking diode and filter before being reduced by a resistordivider circuit and received by the microcontroller 50. The PFCcontroller 34 output voltage is set with a resistor divider to thevoltage sense (VSENSE) pin. The resistor values can be selected by thefollowing equation:

R _(FB2)=(V _(REF) R _(FB1))/(V _(OUT) −V _(REF)) wherein V _(REF)=5 V.

The PFC controller 34 is powered by the VBUS, wherein the maximum inputvoltage for the PFC controller 34 is 22 V and the VBUS provides a 28 Voutput signal. Therefore, the voltage common collector (VCC) of the PFCcontroller 34 is protected with a bipolar junction transistor (BJT)wherein the base is clamped to 15.7 V (i.e., the VCC voltage to theregulator can not exceed 15.7 V). The PFC controller 34 can use twovoltage control loops including an inner current loop and an outer loop.The inner control loop can include an external boost inductor and acurrent sensing resistor in addition to an internal current averagingamplifier and a PWM comparator. The inner control loop shapes an averageinput current to match an input sinusoidal voltage thereby placing theinput current in phase with the input voltage. External compensation forthe inner control loop can be applied to the PFC controller 34 currentcompensation (ICOMP) pin such that the output of the current averagingamplifier is coupled to the ICOMP pin. The outer control loop caninclude an external resistor divider sensing stage, an internal voltageerror amplifier and a non-linear gain generator. An internal erroramplifier and a 5 V reference can be used to provide the outer loop tocontrol the output voltage. External compensation for the outer loop canbe applied by the PFC controller 34 voltage compensation (VCOMP) pin.

The PFC controller 34 can include several fault protection featuresincluding, but not limited to, a VCC under voltage lockout (UVLO); anoutput overvoltage protection (OVP); an open loop protection (OLP);current sense (ISENSE) open-pin protection (ISOP); an ICOMP open-pinprotection (ICOMPP); and a high temperature fail-safe.

The UVLO maintains the PFC controller 34 in an off state until the VCCvoltage exceeds an 11.5 V turn on threshold. The PFC controller 34 shutsdown when the VCC voltage falls below a 9.5 V threshold. The typicalhysteresis for the UVLO is 1.7 V. The PFC controller 34 provides twolevels of output OVP. For example, the PFC controller 34 enters astandby mode when the output voltage on the VSENSE pin exceeds 107% ofthe 5 V reference voltage such that the VCOMP pin is rapidly dischargedthrough an internal 4 kΩ resistor to ground. If the voltage on theVSENSE pin exceeds 109% of the reference voltage, the PFC controller 34gate is disabled (thereby turning off the MOSFET) until the voltage onthe VSENSE pin drops below 102% of the 5 V reference voltage.

Under the OLP protection feature, the PFC controller 34 would also enterthe standby mode (which would stop the PWM switching), if output voltagefeedback components to the VSENSE pin were to fail (e.g., the voltage onthe VSENSE pin falls below 0.82 V) or the components are not installed.The ISOP protection feature causes the PFC controller 34 to enter thestandby mode (which would stop the PWM switching), if current feedbackcomponents to the ISENSE pin were to fail or not be installed.Specifically, if the components were to fail or not be installed, aninternal pull up source would drive the voltage on the ISENSE pin above0.085 V such that the PFC controller 34 would enter the standby mode.The ICOMPP protection feature also causes the PFC controller 34 to enterthe standby mode. Specifically, when the voltage on the ICOMP pin fallsbelow 0.2 V (e.g., the pin shorts to ground), the PWM switching ishalted and the PFC controller 34 enters the standby mode.

The high-temperature, fail-safe protection feature causes the PFCcontroller 34 to enter the standby mode when LED PCBA 16 exceeds atemperature threshold (e.g., 95° C.). The PFC controller 34 enters thestandby mode when the VCOMP pin is pulled low via an n-channel FET thatis connected to an open drain pin of the high temperature shutdowncircuit 76. The PWM switching is halted and the VBUS voltage falls fromthe 28 V boosted voltage to a peak voltage of the 120 Hz rectifiedvoltage (˜20 V) when the PFC controller 34 is in the standby mode. TheVBUS voltage can power the current buck regulators 60. When the VBUSvoltage falls from the 28 V boosted voltage, the VBUS voltage fallsbelow the UVLO threshold thereby causing the current buck regulators 60to turn off which in turn causes the LED strings 74 to turn off.

The VBUS voltage can also be monitored by the microcontroller 50 via theVBUS voltage monitor 38. For example, the microcontroller 50 can asserta low signal on a pin coupled to the VBUS voltage monitor 38 output whenthe microcontroller 50 detects a voltage drop of the VBUS voltage fromthe 28 V boosted voltage. This in turn causes the VCOMP pin to be pulledlow. Accordingly, the current buck regulators 60 will turn off which inturn causes the LED strings 74 to turn off.

The 3.3 V linear voltage regulator 40 regulates the bridge rectifiercircuit 32 rectified voltage output and can be any suitable 3.3 V linearvoltage regulator. When power to the underwater light is applied, theinput to the 3.3 V linear voltage regulator 40 is provided by the inputrectified voltage via a blocking diode. When power is removed, the 3.3 Vlinear voltage regulator 40 can remained powered for 15 seconds via acharge stored on a 220 μF capacitor coupled to its input. The output ofthe 3.3 V linear voltage regulator 40 provides 3.3 V to themicrocontroller 50, dual inverters, a 60 Hz line frequency signal to themicrocontroller 50, a JTAG programming header, the EEPROM 72 clock anddata lines, and a RESET pin of the microcontroller 40.

FIG. 12 is a circuit diagram of the high temperature shutdown circuit 76of the LED PCBA 16 of FIG. 6. The high-temperature shutdown circuit 76can include a 0.1 μF capacitor connected in series with a 3.3 V inputvoltage signal which are collectively coupled to the V+ pin of the hightemperature shutdown circuit 76. The high temperature shutdown circuit76 is a fail-safe that is implemented if the firmware is incapable ofaccurately monitoring and regulating the temperature of the LED PCBA 16.As mentioned above, the high temperature shutdown circuit 76 causes thePFC controller 34 to enter the standby mode when LED PCBA 16 exceeds atemperature threshold (e.g., 95° C.). The PFC controller 34 enters thestandby mode when the VCOMP pin is pulled low via an n-channel FET thatis connected to an open drain pin of the high temperature shutdowncircuit 76. When the PFC controller 34 enters the standby mode, the buckcurrent regulators 60 enter an off state causing the LED strings 74 tobe turned off. The high temperature shutdown circuit 76 can be set tohave a 10° C. hysteresis.

FIG. 13 is a circuit diagram of the EEPROM 72 of the LED PCBA of FIG. 6.The EEPROM 72 can include 3.32 kΩ resistors 120 a and 120 b and a 0.1 μFcapacitor 122 coupled to its output pins. For example, the 0.1 μFcapacitor 122 can be connected in series with a 3.3 V input voltagesignal coupled to the VCC pin of the EEPROM 72. The color tables for theunderwater light can be programmed into the EEPROM 72 on the LED PCBA 16as opposed to being programmed into the microcontroller 50 on thecontroller PCBA 12. Accordingly, a predetermined set of color tablevalues can be coded into the EEPROM 72. Alternatively, an automated testfixture can measure and then program color table values into the EEPROM72 that are specific and unique to each LED PCBA 16 based on a lumenoutput of the LED strings 74.

Having thus described the present disclosure in detail, it is to beunderstood that the foregoing description is not intended to limit thespirit or scope thereof.

What is claimed is:
 1. An underwater light, comprising: a controllerprinted circuit board assembly (PCBA), including: a microcontrollersubsystem including a microcontroller, a light-emitting diode (LED)driver subsystem in communication with the microcontroller subsystem andincluding a plurality of buck regulators, the LED driver subsystemreceiving pulse-width modulated (PWM) signals from the microcontrollersubsystem and being controlled by the PWM signals, and a power subsystemproviding power to the microcontroller subsystem and the LED driversubsystem, the power subsystem including a filter, a bridge rectifier, apower factor correction controller, a line frequency detectionsubsystem, a linear voltage regulator, a line voltage monitor, and a busvoltage monitor; an LED printed circuit board assembly (PCBA) incommunication with the controller PCBA, the LED PCBA including: aplurality of LED strings in communication with and driven by the LEDdriver subsystem of the controller PCBA, a plurality of thermistors incommunication with the microcontroller subsystem of the controller PCBA,the plurality of thermistors measuring temperatures of the plurality ofLED strings and communicating a plurality of LED temperature signals tothe microcontroller subsystem, the microcontroller subsystem controllingoperation of the LED driver subsystem in response to the plurality ofLED temperature signals, an electrically-erasable, programmable,read-only memory (EEPROM) circuit in communication with themicrocontroller subsystem, the EEPROM circuit storing a plurality ofcolor table values for controlling colors of light emitted by theplurality of LED strings, the microcontroller subsystem reading theplurality of color table values from the EEPROM circuit and controllingthe LED driver subsystem in response to the plurality of color tablevalues; a high-temperature shutdown circuit in communication with themicrocontroller subsystem of the controller PCBA, the high-temperatureshutdown circuit issuing a shutdown signal to the microcontrollersubsystem in response to a temperature threshold of the LED PCBA beingexceeded, an optically-transparent potting compound encapsulating theLED PCBA, the EEPROM circuit and the high-temperature shutdown circuitbeing powered by the power subsystem of the controller PCBA; and aconnector connecting the controller PCBA to the LED PCBA, the connectorcommunicating the LED temperature signals from the plurality ofthermistors, control signals between the EEPROM circuit and themicrocontroller subsystem, the shutdown signal from the high-temperatureshutdown circuit, and LED drive signals between the LED driver subsystemand the plurality of LED strings.